1. Field of the Invention
This application relates to the use in current sensors of optical devices that transform light between linearly polarized and elliptically polarized states.
2. Description of Related Art
Devices that transform linearly polarized light to circularly polarized light and the reverse are known in the literature. To make such optical devices, one may use one birefringent fiber with two beams of light of equal frequency and amplitude (or, equivalently, one beam that is the vector sum of these two beams). If the two beams are propagated perpendicular to an optic axis, circularly polarized light may result. Alternatively, linearly polarized light may be transformed to circularly polarized light by using one beam and two fibers.
In practice, constructing a single-beam transformer of linearly to circularly polarized light involves first starting with a length of transforming fiber greater than a predetermined length, and performing several iterations of cutting and measuring polarization until the polarization is deemed to be circular to within some specification. Needless to say, this is a tedious and lengthy procedure requiring lots of guesswork.